Since (meth)acrylic polymer is transparent and it forms a film and has good workability, it has been widely used as a coating material, an adhesive material, a material for ink, a material for external use on skin, a cosmetic material, etc. However, since acrylic resin has high polarity, it has also had many problems. As such, various copolymers have been developed so far. Examples of the thus developed copolymers include: an acryl-silicone-based graft copolymer obtained by radical copolymerization of a dimethylpolysiloxane compound having a radically polymerizable group at one end of a molecular chain thereof and a radically polymerizable monomer having acrylate and/or methacrylate as a main body (see for example, Patent Document 3); and an amphiphilic block copolymer comprising a polysiloxane block and a cationic block (see for example, Patent Document 2).
Meanwhile, there are various types of cosmetics. Specific examples of a leave-in type hair cosmetic that intends to be mainly used out of the bath include styling spray, styling mousse, hair mist, hair wax, hair gel, hair oil, and hair treatment.
In recent years, with regard to such out-bath type hair cosmetics, there has been an increasing demand for a hair styling product capable of rearranging hair without flaking, thereby easily arranging hair style, a hair conditioner for dry hair, a hair styling product for thinning hair, and the like. As a result, with regard to a hair styling product, it has been desired to develop a non-sticky elastic resin so as to allow hairs to softly adhere to one another without fixing them strongly to impart voluminousness and airly feeling from hair roots, or so as to impart the bounce and resilience of healthy hair to damaged hair. In addition, with regard to a hair conditioner, it has been desired to develop a resin having high affinity for silicone as a conditioning ingredient for the repair of hair surface and the improvement of the touch.
In order to meet these needs, various types of resins have been developed. For some examples, there are the silicone-based copolymers described in above-mentioned patent documents.
For example, Patent Document 1 describes a silicone copolymer consisting of: 0.1% to 40% one or more silicone macromonomers having the following general formula (1):R1R2SiO(SiR2O)nSiR2R1  (1)[wherein R represents monovalent, linear or cyclic, and Si—C-bound or optionally substituted hydrocarbon groups, which are independent from one another, or alkoxy groups each having 1 to 18 carbon atoms; R1 represents a polymerizable group; and n represents 10 to 1000]; B) 0.5% to 10% radically polymerizable carboxylic acid selected from the group consisting of crotonic acid and acrylic acid, and optionally further containing other hydrophilic monomers; and C) 30% to 99.4% hydrophobic monomer comprising vinyl acetate and optionally further comprising other hydrophobic monomers.
Moreover, Patent Document 2 describes an amphiphilic block copolymer comprising
a) at least one siloxane block polymer represented by the following formula (I):
(wherein R1 and R2 each independently represent an alkyl group, an alkoxy group, a phenylalkyl group, an aryl group, an aryloxy group, an alkylaryl group, an alkylamine group, an alkylhydroxy group, a polyoxyalkylene group, or a polyalkylenepolyamine group; and n represents a number between 2 and 10,000), andb) a cationic block polymer formed with at least one cationic monomer represented by the following formula (II):
(wherein R3 and R4 each independently represent a hydrogen atom or an alkyl group containing 1 to 4 carbon atoms; R5 and R6 each independently represent a hydrogen atom, or an alkyl group, a hydroxyalkyl group, a carboxyalkyl group, a carboxyamidealkyl group or an alkoxyalkyl group, which contains 1 to 18 carbon atoms; and Y− represents an anion).
However, these silicone-based copolymers have not sufficiently satisfied the aforementioned needs.
In addition to the aforementioned patent documents, the following publications describe a copolymer that can be used as a cosmetic, a hair wash, or the like, which has a repeating unit that is partially the same as that of the cationic (meth)acrylic silicone-based graft copolymer according to the present invention. Nevertheless, none of such publications describe the same copolymer as that of the present invention.
(Patent Document 3)
An acryl-silicone-based graft copolymer obtained by radical copolymerization of a dimethylpolysiloxane compound having a radically polymerizable group at one end of a molecular chain thereof, represented by the following general formula (1):
and a radically polymerizable monomer comprising, as a main body, acrylate and/or methacrylate.(Patent Document 4)
A cationic graft (co)polymer obtained by polymerization of a macromonomer comprising, as essential components,
(A) at least one monomer unit having a cationic group represented by the following general formula (I):
or the following formula (II):
and(B) at least one monomer unit having a nonionic group represented by the following formula (III):
or the following formula (IV):
